In the novel Harry Potter and the Prisoner of Azkaban, werewolves are a key part of the plot and are discussed in detail. In the wizarding world, werewolves are humans that transform during a full moon into a creature that is taller and altogether scarier than an ordinary wolf.  The process of transformation is shown very clearly and is very painful, especially during early years. These creatures hunt during their transformation but do not kill for sport, though they will attack humans more often than they will attack other animals. They do not retain any of their humanity while transformed and will not recognize even their closest of friends. Most werewolves are entirely normal people when not under the influence of a full moon, although in some cases, such as Fenir Greyback, a villain in the series, they seem to be perpetually stuck between the two. In this world, there is a potion that can reduce the effects of the transformation and cause the werewolf to simply become a harmless wolf until the full moon sets. However, there is no way to completely cure someone of their lycanthropy.

In Bisclavret, the transformation does not affect the man’s rationality or intelligence in the slightest. It appears that the change is only physical and that the mind remains fully functioning at human level. This is very different from the werewolves of Harry Potter because Bisclavret has the ability to recognize people such as his wife and the king while in animal form, but in Harry Potter, the werewolf attacks his best friend and his students. While Bisclavret adapts to living in the castle and remembers everything about how his wife has wronged him, the werewolf in Harry Potter only responds to aggression and the sound of another werewolf in the distance. These two stories represent very different versions of this mythological creature which has been around for centuries.